Combination lock switch



July 12, 1932. MASON 1,867,415

COMBINATION LOCK SWITCH Filed Sept. 18, 1929 if, J

Patented July 12, 1932 barren stares Pa'ran r oerica WILLIAM K. MASON, 'OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR USO-AMERICAN ELEC- TRICAL COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHU- SETTS COMBINATION LOCK SWITCH Application filed September 18, 1929. Serial mane.

This invention relates to an electric switch which may be controlled after the manner of a combination lock by rotating a knob or the like through certain predetermined angles which may be indicated conveniently by a dial and index. According to the invention a normally open switch, suitably enclosed to prevent unauthorized access thereto, may be closed by correct manipulation of an exposed operating knob, but the correct combination of numbers on the dial must-be known to the operator to enable him to close the switch. Among the various uses to which such aswitch may be put, an illustrative use is found in connection with a burglar alarm installation in a building. Such an alarm system may include a closed switch associated with each window and door in such a way. that if any one of the switches is opened by motion of a' door or window, the alarm is' actuated. hen a building is left over night with such an alarm system in operative condition, it is desirable to provide entrance'for authorized persons without setting off the alarm. To this end a shunt may be provided around the alarm switch attached to the entrance door so that when the shunt circuit is closed, the door switch may beopened without actuating the alarm. The shunt switch may .be mounted at any convenient place within the building, preferably on or near the door itself. An operating spindle extends to the outside of the building and may carry a knob for actuation of the switch elements.v The latter may be pushed around until each is individually touching a corresponding contact point, the shunt circuit being thereby closed. In order to accomplish this,however,

the operator must know at what points the rotation of the knob must be reversed. There is no opportunity afforded to determine the correct combination by trial and error since if the circuit is not closed on the first attempt, the opening of the door starts the alarm. 1

F or a more complete understanding of the invention, reference may be had to the description thereof which follows, and to the drawing, of Wl1lCl1,

Figure 1 is an elevation of the external aspect of a switch embodying the combination as installed.

, Figure 2 is Figure 1. Figure 3 is Figure 2;

Figure 4 is a fragmentary perspective view a section on the line 2+2 of a section on the line 33 of of the working portions of the switch.

a section on the line 55 of faceto face. These disks may be centrally;

perforated as at 15 tov receive a spindle 16 by which the switch is operated, Loosely mounted on the spindle 16 are a pair of arms 17 18, these arms being independently revoluble aroundthe spindle 16. Since. the spindle 16-mayconveniently be made of metal, a suitable sleeve 19 of insulating material-such as fiber, bakelite, or the like may be carried on the spindle, as shown in Figure Over the sleeve 19 may be a metal sleeve 20 having end flanges 21 flush with the opposite ends of the sleeve 19. Themetal sleeve 20 preferably fits within the perforation 15 so that in assembling the device, one of the flanges 21 isformed after the sleeve 20 has been threaded through the perforation 15. Between one of the flanges 21 and the adjacent face of the disks 13, 14 are mounted the arm 17 and a pair of washers 22, one on either side of the arm. The washers 22 are preferably of metal so that while the arm 17 is free to rotate about the sleeve 20, a good electrical contact between the arm and the sleeve is maintained. In like manner the-arm. 18 is mounted on the'sleeve 20 between apair of metal washers 22 on the other side of the disks 13, 14. The arms 17 and 18, as shownin Figure 5, are preferably bent outward away from the disks 13, 14 and are provided respectively with inturned portions 23, 24 which bear against the faces of the disks 13 and 14, respectively, sothat as the arms 17 and 18 are swung around the axis of the spindle 16, their outer ends constantly rub against the faces of the adjacent disks. To this end the arms are preferably made of spring metal. As shown in Figure 4, a metallic contact element is set into the disk 13' so that its face is flush with the outer'face ofthe disk. The element is in the path of the contacting portion 23 of the arm 17, so that when the'arm 17 is swung about the axisof the spindle the end 23 may, come into contact with the element 25. As shown, the element may be extended as at 26 to the rim of the disk 13 where it may be conveniently connected to a suitable wire 27 A similar element 28 may be mounted in the disk 14 so as to hem the path of the contact portion 24.

of the arm 18. This element may have anextension 29 projecting from the rim of the disk and connected to a suitable wire 30. Thus if the wires 27 and 30 are connected into a circuit, there are normally'two gaps in this circuit when the switch is open, one ofv these gaps being between the-arm 17 and the contact element 25', the second gap being between the arm 18 and the element 28. Since the arms 17 and 18 are constantly. connected'electric-ally through the sleeve 20, thecircuit through the wires 27, 30 may be closed by causing the arms 17 and 18 to contact simultaneously with the elements 25 andf28, respectively;

For the purpose of revolving the arms 17 and 18 independently around the axis of thespindle 16, ,I may provide a suitablemember 31 projecting laterally from the spindle 16 and secured thereto. 'As shown, the member.v

31 may be in the'form of a set screw threaded into ,a collar 32 which is mounted on the spindle;16. The set screw 31 may thus not only have the function of adjustably securing the collar 32 to'the spindle 16, but also projects from the spindle sufficiently to hem the path of a portion of thearm 18. Thus if the spindle is rotated, the set screw or abutment member 31 swings around withit and eventually brings up against one side or the other of the arm 18. Continued movement in the same direction will result in a pushing of the arm 18 around the axisof the spindle. If, now, the; direction of rotation of, the spindle be reversed, themember 31 swings away from the arm 18 and leaves the latter motionless. In addition to the set screw 31, I may also provide a second set screw or abutment member 33 which maybe screw-threaded into the collar; 32 at a point diametrically opposite to'the member 31, as shown in Figure 3 or at any other point jdesired; Thus when the member 31 is swung away from contact with thearm 18, the member 33 appreaches the other side of the arm 18 and eventually engages it to swing it in the opposite direction. The-member 33 may also be employed as an additional set screw to insure the firm engagement of the collar 32 on the spindle 16. v i

The arm 17 may also be moved about the axis of the spindle in a similar manner. As shown, a single set screw 34 is provided, this screw being set in a collar-35 which: is on the spindle 16 and may be adjustably secured to the spindle by a set screw 34. A second set screw may be employed opposite the set screw 34 to assist insecuring the collar 35 to the spindle 16, but'if such a set screw be used it is preferred not to have it engage the arm 17. Whenthe spindle isrotated, the abutment member 34 swings around until it engages a sideof the arm 17, whereupon further rotation of the spindle in the same direction results in a swinging of the arm 17 about the axis of the spindle. p

' In order to insulate the arms 17 and 18 and their washers 22' completely from adjacent metallic parts, I may provide a pair of insulating washers 50 of ,fiber, bakelite, or

similar insulating material to cooperate with the lnsulatlng sleeve 19 in preventing a possible short c1rcu1t between the arms 17, 18

I through thecollars 32,35 and the spindle 16.

Since the working mechanism of the switch is normally hidden from view, and since the faces of the contact points 25 are flush with the faces'of the disks 13 and 14, it is necessary for the operator to knowjust how far to turn the spindle 16in order to move the arms 17 and 18 successively -into contact with their respective contact points :25 and 28. The

7 switch, as a'whole, is'intended to be mounted,

'mortised into the housing cover 12 on which the mechanism is mounted. This aligns the mechanism accurately with the hole through the door so that when the spindle 16 is thrust through the door to be connected to-tlie switch -mechan ismin the course of installation it will be properly'ahgned with the hole, and

will not bind therein. Mounted on theouter end portion of'the spindle 16' is a finger knob 37 having a conical portion '38 Wl'l1 ch 1s d1"- vided by peripheral scalemarks which may cooperate with an lndex mark on thedoor or on a sultable plate 39 secured to the door.

' i In operating the switch to close the circuit, the operator turns the knob 37 in a specified direction which depends upon the adjustment of the collars 32iand 35 When the proper scale mark is opposite the index mark, this indicatesthat the abutment member 34 engaged the arm 17 and has swung that arm about the axis of the spindle until the contact end 23 is resting on its contacting element 25 The knob 37 is now reversed leaving the arm 17 in contact with the element 25. This re verse rotation of the knob 37 results in an eventual engagement of the member 31 or 33 with the arm 18, this arm being thereupon revolved around the spindle until the dial indicates that the arm is in contact with its contact element 28. If the rotation of the knob 37 is stopped at this point, both the arms are simultaneously in contact with their respective contact elements so that the circuit is completed through the switch. Any motion of the knob which moves either or both of the arms from their contact elements opens the switch.

A typical use of a switch of this type is illustrated in Figure 6. Herein is shown an alarm circuit 40 having therein a suitable battery 41, or other equivalent source of electrical energy, a number of normally closed switches 42 which may be attached to windows or at other points in a building to open in case the window is tampered with, a similar switch 43 to be mounted on the door customarily used by the occupant of the building for access thereto, and an electromagnetic relay 44 which, as shown, may hold a switch 45 normally open but which allows the switch 45 to t is desirable to provide for the occupant.

of the building means of access thereto without setting OK the alarm 46. For this purpose a shunt circuit 48 may be provided about the switch 43 so that ii' the shunt circuit 48 is closed, the switch 43 may thereupon be opened without setting off an alarm. The shunt circuit 48 may thus comprise a pair of wires 27 and 30 connected to the switch mechanism hereinbefore described. The knob 37 being on the outside of the dooror wall of the building is accessible and may be operated to close the switch, and thus to permit entry into the building without actuating the alarm. operator to know the correct dial numbers; otherwise the arms 17 and 18 are moved past the contact elements 25 and 28 instead of being allowed to rest thereon. The possibility of accidental closing of this switch by random operation of the knob is infinitesimal.

In order to provide against successful operation of the switch by an expert, sensitive to the change of feel of the knob when the arm 17 or 18 passes from the surface of its insulating disk to the surface of its contact element, 1 may provide a number of dummy contact elements 49 having faces flush with the disk 13 or 14 in the same manner as the contact elements 25 and 28. One or two such dummy contact elements may be mounted in each disk or, for further security, a con- It is necessary, however, for the.

switch to be opened rather than a normally i open switch to be closed.- To this end a considerable number of'contact elements may be set intoeach disk, successive elements being sufficiently close togetherto enable the contact'end 23 or 24 to bridge the intervening space 'so that the arm is always in contact with atleast one of the elements in its disk. It all the elements except one in each disk be electrically connected to the lead 26"or 29., the switch will remain closed until the "arms 17 or 18 are in contact with the one contact element in each disk which is not connected to the respective leads. Thus in order to open the switch the correct dial combination must be. known. The invention isnot limited to the particular embodiment herein illustrated and described but includes all such modifications and changes whichfall within the scope of the appended claims.

I claim: V 1. A device of the class described comprising a rotatable spindle, a pair otarms having electrical contact points and loosely mounted torevolve independently about said spindle, a pair oi abutment members proectmg laterally from said spindle and movable'by rotation of the spindle into engagement with said arms respectively,'whereby said arms may be independently moved by rotation of said spindle, a pair of-fixed contact points respectively engageable' by the movable contact pointscar-ried by said arms, means permanently electrically connecting said movable points on both arms; with each other, and means electrically insulating said movable points from said fixed points when not engaged therewith.

2. A device of the class described comprisinga pair of'fixed Contact elements, a rotatable spindle, a pair of arms loosely mounted to revolve independently about said. spindle into and out of contact with said respective contact elements, means permanently electrically connecting said arms with each other, a pair of laterally projecting abutment members mounted on said spindle and angularly adjustable thereabout, each said abutment member being movable in its pathtoengage a respective arm and thereby torevolve the arm thus engaged about the axis of the spindle, and a finger-piece mounted on the end of said spindle.

3. A device of the class described compris- 7 ing a disk of insulating material, a spindle extending loosely through said disk and coaxial therewith, a circularseries of spaced metal elements set flush into each face of said disk symmetrically with respect to said spindle and insulated fromone anothena pair 'ofconducting members swingable about said spindle as an axis in contact respectively with the series of elements in the faces of said disk, means permanently electrically connecting said members, means for connecting a pair of lead wires respectively to one element of each said series and means including a lost motion connection between said spindle and each of said members for swinging said members independently around said spindle.

4.;A device of the class described com- 7 prising a disk of insulating material hav- 7 ments being in the .path of contactof the respective arms, means projecting laterally from said spindle to engage and revolve said arms when the spindle is rotated, andmeans for connecting said'metalelements into an electrical circuit. r r

5. A device of the class described comprising adisk of'insulating material having set-screws having portions projecting from said collars to engage said arms when said spindle is rotated, whereby said arms may be revolved about said spindle.

In testimony whereof have aflixed my signature.

WILLIAM K. MASON. I

aflcentral-aperture, 'a flanged metallic sleeve fitted'in saidaperture-and projecting beyond 1 "both faces of the disk, a sleeve of insulating material fitted 'within said metallic sleeve, the endsof said insulatingsleeve being substantially flush with the ends of said metallic sleeve, a metallic contact arm on each side ofjsaid disk,said arms being loosely mountedon the projecting portions of said metallic sleeve to swing about the axis thereof and to have permanent electrical contact therewith, each said armhaving an inturned' end bearing against a face of the disk, a contactpoint set flush in each face of the disk in the path of contact with the disk'of the respective arm, perforated insulating washers against the ends of said sleeves, a

spindle projecting through said washers and sleeves, a pair, of collarsadjustably fixed on 9 said spindle and respectively adjacent to said washers, and means on said spindle for separatelyen gaging'said arms to rotate said arms respectively into contact with said contact points. p Q V j 6. In a combination lock switch having a disk of insulating material, metal'contact 7 elements set into the opposite faces ofsaid disk, a rotatable spindle extending through the center of said disk, and arms loosely revoluble about the axis or" said spindle into and out of contact with said metal elements; 'acollar mounted on said spindle on each side of the disk, and set-screws in said collars adjustably securing said collars in place, said 

